【作者】 李燕；

【导师】 严义；

【作者基本信息】 杭州电子科技大学 ， 计算机系统结构， 2009， 硕士

【摘要】 随着计算机和微电子技术的进一步发展,PLC技术和嵌入式系统结合成为了目前PLC发展的新方向。嵌入式PLC的应用相当广泛、应用场合多样。虽然各种嵌入式PLC产品的组成形式和功能特点各不相同,但它们总体结构上基本是相同的,一般由中央处理器(CPU)、存储器、输入/输出系统、通信接口、内部电源等部分组成。一个PLC中多个具有相同结构的输入/输出功能模块,在不同的PLC中可能存在相同的通信功能模块和电源功能模块。即在PLC硬件设计过程中存在很多重复的设计,并且在传统设计过程中往往会存在很多由人为因素造成的设计错误,如由于连接关系复杂造成的网络标号错误,或在拷贝相同电路时因拷贝数量大而疏忽了元件的更名造成元件名重复。在电路板布局过程中,将元件按就近原则布局的过程就要耗费设计人员大量的时间。为实现硬件电路模块的设计复用,提高电路设计正确性,本文提出了一种基于构件的电路设计平台。首先我们对嵌入式PLC的基本硬件电路模块进行研究,发现这些模块具有以下三个共同的特点:(1)具有较高重复性;(2)具有通用性;(3)具有独立性。这些特点与构件的基本特征吻合,说明将这些模块封装成构件用于原理图的设计具有可行性。然后在对软件构件技术研究基础上提出适合硬件电路开发的硬件电路构件(HWCC)的概念模型以及其对应的构件库和构件组装方案。我们以现有电路设计软件的网络表文件、封装库文件、电路板文件作为二次开发接口,利用外部开发机制实现了基于构件的嵌入式PLC电路设计平台的开发。平台主要由封装库、构件库管理系统、原理图设计器、解析器四部分构成。封装库实现封装库文件的导入及存储;构件库管理系统实现构件的制作、构件的存储、构件的动态修改以及构件的提取;原理图设计器以可视化图形方式实现基于构件的电路原理图设计;解析器负责原理图设计结果的分析,最终生成对应的电路板文件。经过实际的电路设计实践证明,该平台有效降低原理图复杂度,提高电路设计正确性,缩短电路板开发周期。更多还原

【Abstract】 With the development of computer and microelectronics technology, the combining of PLC technology and embedded system become a new direction of the current PLC development, which is widely applied at various occasions. Although different embedded PLC products vary in terms of forms and function, they share the same overall structure. Basically, the embedded PLC is composed of the central processing unit (CPU), memory, I/O(input /output) system, communication interface, internal power module and other optional components. Many I/O modules with the same structure in a PLC would have the same communication and power module in different PLC. In other words, there will be many repetitive hardware designs of PLC. In addition, in the traditional design process, there will be many errors caused by human mistakes in traditional design process. For example, the network label errors caused by complex connection relationship, or duplicating component names caused by negligence of the component rename when a large number of copying components are copied from the same circuit. It will cost a lot of time for the designer to position the components according to the principle of the nearest.In order to reuse the hardware circuit module and improve the correctness of circuit design, we propose a circuit design platform which is based on design components. Firstly, the basic hardware circuit modules of embedded PLC are studied, we found that these modules have three common characters: high repeatability, generability, and independence. These features are in accord with the essential characteristics of the software components, which shows the feasibility to encapsulate these modules into components for the schematic design. Then, a conceptual model of hardware circuit component (HWCC) which supports hardware circuit is proposed on the basis of the research of the software component, component library of the corresponding and component assembling program. The current circuit design tools’network files, footprint library files, and circuit board files are used as interfaces of the secondary development method. And the external development method is used for developing the platform for the embedded PLC circuit design which is based on components. This platform is composed of footprint library, manage system of component library, circuits schematic designer, and parser. The footprint library is responsible for the footprint library files’import and storage. The manage system of component library is responsible for components’making, storage, dynamic modification and extraction. The circuits schematic designer use a graphical user interface for the component based designing of circuit schematic. The parser is in charge of the analysis of the result of the circuit schematic design, and generating corresponding circuit board file.The circuit development experiments show that this proposed platform can reduce the complexity of the circuit design, improve the correctness of circuit design and shorten the development time of circuit design.更多还原